Magnetic Resonance Imaging of the Pediatric Knee

Imaging of sports injuries in adolescents

Musculoskeletal injuries in adolescents tend to occur in particular locations and have distinct characteristics, as they affect an immature skeleton. Increased engagement in sports, extended training and competition periods, and early specialization in specific sports, among other factors, have contributed significantly to the rise in musculoskeletal sports injuries in adolescents. Furthermore, females show a particularly pronounced increase in sports participation, where anatomical and hormonal factors play crucial roles in the development and increased frequency of sports-related injuries. Consequently, there is a growing demand for diagnostic imaging techniques. Musculoskeletal and pediatric radiologists require a comprehensive understanding of intrinsic and extrinsic risk factors and the successive stages of skeletal development that can influence the specific characteristics of sports injuries in adolescents. These aspects are crucial for the diagnostic, prognostic, and therapeutic management of these injuries and for mitigating chronic conditions that could compromise future sports participation. This review analyzes the primary musculoskeletal injuries in adolescent athletes and highlights the pivotal role of different imaging methods in their diagnosis and management.

Social deprivation index affects time to MRI after knee injury in pediatric patients and is predicted by patient demographics

OBJECTIVES

This study aims to characterize the association between the timing of MRI ordering and completion for pediatric knee injuries and Social Deprivation Index (SDI), which is a comprehensive, validated, county-level, measure of socioeconomic variation in health outcomes based upon combining geography, income, education, employment, housing, household characteristics, and access to transportation.

METHODS

A retrospective chart review was completed of patients 21 years old and younger from our institution with a history of knee sports injury (ligamentous/soft tissue injury, structural abnormality, instability, inflammation) evaluated with MRI between 5/26/2017 and 12/28/2020. Patients were from three states and attended to by physicians associated with an urban academic institution. Patients were assigned SDI scores based on their ZIP code. Excluded from the study were patients with a non-knee related diagnosis (hip, foot, or ankle), patients from ZIP codes with unknown SDI, and non-sports medicine diagnoses (tumor, infection, fracture).

RESULTS

In a multivariate regression analysis of 355 patients, increased SDI was independently associated with increased time from clinic visit to MRI order (p = 0.044) and from clinic visit to MRI completion (p = 0.047). Each 10-point increase in SDI (0-100) was associated with a delay of 7.2 days on average. SDI itself was found to be associated with a patient's race (p < 0.001), ethnicity (p < 0.001), and insurance category (p < 0.001).

CONCLUSION

Increased SDI is independently associated with longer time from clinic visit to knee MRI order and longer time from clinic visit to knee MRI completion in our pediatric population. Recognizing potential barriers to orthopedic care can help create the change necessary to provide the best possible care for all individual patients.

Quantitative Skeletal Imaging and Image-Based Modeling in Pediatric Orthopaedics

PURPOSE OF REVIEW

Musculoskeletal imaging serves a critical role in clinical care and orthopaedic research. Image-based modeling is also gaining traction as a useful tool in understanding skeletal morphology and mechanics. However, there are fewer studies on advanced imaging and modeling in pediatric populations. The purpose of this review is to provide an overview of recent literature on skeletal imaging modalities and modeling techniques with a special emphasis on current and future uses in pediatric research and clinical care.

RECENT FINDINGS

While many principles of imaging and 3D modeling are relevant across the lifespan, there are special considerations for pediatric musculoskeletal imaging and fewer studies of 3D skeletal modeling in pediatric populations. Improved understanding of bone morphology and growth during childhood in healthy and pathologic patients may provide new insight into the pathophysiology of pediatric-onset skeletal diseases and the biomechanics of bone development. Clinical translation of 3D modeling tools developed in orthopaedic research is limited by the requirement for manual image segmentation and the resources needed for segmentation, modeling, and analysis. This paper highlights the current and future uses of common musculoskeletal imaging modalities and 3D modeling techniques in pediatric orthopaedic clinical care and research.

The Magnetic Resonance Imaging Pattern of the Lesions Caused by Knee Overuse in the Pediatric Population

Background and Objectives: Excessive use of the knee in patients with immature locomotor systems leads to a whole spectrum of morphological changes with possible consequences in adulthood. This study aimed to examine the morphological pattern in magnetic resonance imaging (MRI) that is associated with recurrent pain due to increased physical activity in children. Materials and Methods: This was a retrospective study conducted among pediatric patients treated at the University Children’s Hospital in Belgrade in 2018 and 2019. MRI findings of patients who reported recurrent pain in the knee joint during physical activity and who were without any pathological findings on both clinical examination and knee radiographs were included in the study. Results: MRI findings of 168 patients (73 boys and 95 girls, mean age 14.07 ± 3.34 years) were assessed. Meniscus and cartilage lesions were the most commonly detected morphological findings: meniscus lesions in 49.4%, cartilage ruptures in 44.6%, and cartilage edema in 26.2% of patients. The medial meniscus was more often injured in girls (p = 0.030), while boys were more prone to other joint injuries (p = 0.016), re-injury of the same joint (p = 0.036), bone bruises (p < 0.001), and ligament injuries (p = 0.001). In children older than 15 years, tibial plateau cartilage edema (p = 0.016), chondromalacia patellae (p = 0.005), and retropatellar effusion (p = 0.011) were detected more frequently compared to younger children. Conclusions: Children reporting recurrent knee pain due to increased physical activity, without any detected pathological findings on clinical examination and knee radiography, may have morphological changes that can be detected on MRI. Timely diagnosis of joint lesions should play a significant role in preventing permanent joint dysfunction in the pediatric population as well as in preventing the development of musculoskeletal diseases in adulthood.

Targeted rapid knee MRI exam using T2 shuffling

BACKGROUND

MRI is commonly used to evaluate pediatric musculoskeletal pathologies, but same-day/near-term scheduling and short exams remain challenges.

PURPOSE

To investigate the feasibility of a targeted rapid pediatric knee MRI exam, with the goal of reducing cost and enabling same-day MRI access.

STUDY TYPE

A cost effectiveness study done prospectively.

SUBJECTS

Forty-seven pediatric patients.

FIELD STRENGTH/SEQUENCE

3T. The 10-minute protocol was based on T2 Shuffling, a four-dimensional acquisition and reconstruction of images with variable T2 contrast, and a T1 2D fast spin-echo (FSE) sequence. A distributed, compressed sensing-based reconstruction was implemented on a four-node high-performance compute cluster and integrated into the clinical workflow.

ASSESSMENT

In an Institutional Review Board-approved study with informed consent/assent, we implemented a targeted pediatric knee MRI exam for assessing pediatric knee pain. Pediatric patients were subselected for the exam based on insurance plan and clinical indication. Over a 2-year period, 47 subjects were recruited for the study and 49 MRIs were ordered. Date and time information was recorded for MRI referral, registration, and completion. Image quality was assessed from 0 (nondiagnostic) to 5 (outstanding) by two readers, and consensus was subsequently reached.

STATISTICAL TESTS

A Wilcoxon rank-sum test assessed the null hypothesis that the targeted exam times compared with conventional knee exam times were unchanged.

RESULTS

Of the 49 cases, 20 were completed on the same day as exam referral. Median time from registration to exam completion was 18.7 minutes. Median reconstruction time for T2 Shuffling was reduced from 18.9 minutes to 95 seconds using the distributed implementation. Technical fees charged for the targeted exam were one-third that of the routine clinical knee exam. No subject had to return for additional imaging.

DATA CONCLUSION

The targeted knee MRI exam is feasible and reduces the imaging time, cost, and barrier to same-day MRI access for pediatric patients.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 6 J. Magn. Reson. Imaging 2019.

Unusual Presentations of Focal Periphyseal Edema Zones: A Report of Bilateral Symmetric Presentation and Partial Physeal Closure

Focal periphyseal edema (FOPE) zones are areas of periphyseal edema seen near the time of physeal closure which are believed to be a physiologic phenomenon related to changes in distribution of forces around the physis as it closes. Since the original case series describing these areas of periphyseal edema, there has been little published in regard to FOPE zone outside of review articles. We present a set of three patients identified with focal periphyseal edema zones around the knee and compare our findings with the initial case series. We include a patient presenting with bilateral, nearly symmetric, focal periphyseal edema zones of the proximal tibia physis and a patient with partial closure of the physis at time of presentation, which were not reported in the original case series.